Air cushioned kicker feed bar

ABSTRACT

A feed bar assembly for apparatus for performing operations on sheet material including a feed station wherein a plurality of sheets are supported in a stack and means for reciprocating the feed bar to advance single sheets to a pair of feed rolls comprising an elongated bar and a plurality of feed fingers mounted along the length of said bar, each of said fingers including a pivotally mounted plate member and a feed clip mounted on said plate member having a pickup portion adapted to engage an edge of one sheet at the bottom of the stack to advance the same to the feed rolls and actuator means adapted to pivot said feed fingers upwardly to insure positive engagement of each of said feed fingers with the edge of one sheet.

United States Patent Henc et a].

[ July 11, 1972 [54] AIR CUSHIONED KICKER FEED BAR [72] Inventors:Edward V. Henc, 302 Netherington Drive, Broomall, Pa. 19008; Edmund F.X. Devlin, Manoa, Pa.

[73] Assignee: said Henc, by sald Devlin [22] Filed: Feb. 16, 1970 [21]Appl. No: 11,596

Primary Examiner-Joseph Wegbreit Attorney-Howson and Howson [5 7]ABSTRACT A feed bar assembly for apparatus for performing operations onsheet material including a feed station wherein a plurality of sheetsare supported in a stack and means for reciprocating the feed bar toadvance single sheets to a pair of feed rolls comprising an elongatedbar and a plurality of feed fingers mounted along the length of saidbar, each of said fingers including a pivotally mounted plate member anda feed clip mounted on said plate member having a pickup portion adaptedto engage an edge of one sheet at the bottom of the stack to advance thesame to the feed rolls and actuator means adapted to pivot said feedfingers upwardly to insure positive engagement of each of said feedfingers with the edge of one sheet.

11 Claims, 11 Drawing Figures FIG. I.

INVENTORI EDWARD V. HENC EDMUND F.X. DEVLIN ATTYS P'A'TENTEnJuL 11 I9723 6 75.918

SHEET 3 BF 4 m M V FIGS. 5

EDWARD V. HENC KY EDMUND EX. DEVLIN W2? ATTYS PATENT'EDJUL 11 1272 3,675 9 l 8 SHEET u 0F 4 i Ta INVENTOR.

EDWARD V. HENC EDMUND F X. DEVLIN ATTYS AIR CUSI'IIONED KICKER FEED BARThe present invention relates to improvements in machines for performingcutting, creasing, printing, embossing or like operations on sheetmaterials such as corrugated board or the like. More particularly, thepresent invention is directed to an improvement in the blank feedingmechanism for such machines.

Typically, these machines comprise a main frame having a feed table atone end thereof for a plurality of work sheets or blanks arranged in astack, means for maintaining the box blanks in a vertical stack and feedmeans in the form of a feed bar adapted for reciprocating movementbetween the rear edge of the stack and a point short of the front stopsconfining the stack for advancing the lowermost sheet from the stack toa pair of feed rolls which in turn advance a single sheet at a timethrough the machine for other operations such as cutting, creasing,printing, embossing or like operations.

The conventional feed bar which is shown, for example, in U.S. Pat. Nos.3,004,456 and 1,797,692 generally comprises a plurality of resilientfingers which are generally biased to extend rearwardly and upwardly atan angle from the forward edge of the bar. Each of the fingers has aconcave tip at its upper rear end which at its forward edge forms ashoulder for engaging the rear edge of the lowermost sheet of the stack.In the fully retracted position of the bar, the fingers are disposed sothat the shoulders lie rearwardly of the rear edge of the stack.Accordingly, upon forward movement of the bar from this position, theshoulders of the fingers engage with the rear edge of the lowermostsheet and slide a sheet forwardly from under the stack and into the nipof the feed rolls. Upon retractive movement of the bar the upper concavefaces of the tip elements ride freely on the underside of the overlyingand now lowermost sheet of the stack.

While the conventional feed bar arrangement described above in mostcases has been satisfactory for feeding sheet material, in someinstances where the sheet material is warped, it has been found that therearmost edge of the sheet is not engaged by all of the spring fingers,and consequently, during feeding movement of the feed bar, the sheetcocks and will in some instances jam the machine. This, of course, isundesirable since it interrupts operation of the machine and oftentimesthe task of removing the cocked sheet from the machine is timeconsuming. In some instances it has been found that improper feeding canresult in damage to parts of the machine which, of course, results infurther down time on the machine for repair purposes.

In apparatus having the conventional spring biased feed fingers it hasbeen found that in some instances not all of the feed fingers engage therear edge of the blank during the feeding by reason of the fact that thesheet material may be slightly warped. As a result of this, the sheet isslightly cocked or skewed during the feeding operation and is not inproper registry during passage through the apparatus. This isundesirable for the reason that improper registry or alignment duringtraverse of the blank through the machine may result in misalignment ofthe corresponding blanks and/or printing on a blank adapted to be formedinto a box or the like. If the misalignment is severe enough, it canresult in the blank being rejected, or at best it is an inferiorproduct.

The present invention is directed to an improvement in the feedmechanisms for machines of the above type which incorporates novelfeatures of construction and arrangement eliminating the problem ofjamming caused by misfeeding of box blanks. To this end, in accordancewith the present invention, the feed bar comprises a plurality ofpivotally mounted feed fingers, each of the feed fingers having ahydraulically actuatable system for actuating the feed fingers intopositive pressure engaging relation with the lowermost blank on thestack at the feed table. Each of the hydraulic actuators is operatedfrom a common source whereby the heel of the radiused feed clip followsthe contour of the lowermost sheet on the stack to provide positiveactuation by all of the feed fingers and eliminate the problem ofcocking and subsequent jamming of the machine caused, for example, by awarped blank. In accordance with the present invention, the pickup faceof all of the feed fingers engage the rear edge of a blank irrespectiveof whether the blank is warped thereby insuring positive or properregistry of the sheet during movement through the apparatus. This, ofcourse, avoids the problem of improper location or orientation of foldlines resulting from a creasing operation, cuts in the blank during thecutting operation. It also insures proper arrangement of the printing ifthe blank is being printed. The present invention also provides a novelsystem for effecting skip feed consisting of a proximity sensoroperatively associated with the stroke of the feed bar which selectivelyinterrupts flow of air to the actuators so that the fingers are in aretracted position for every other stroke. This is a useful innovationin cases where large blanks are being fed through the machine.

These and other objects of the present invention and various featuresand details of the operation and construction thereof are hereinaftermore fully set forth with reference to the drawings, wherein;

FIG. 1 is a plan view of the feed section of a machine for performingcutting, creasing, printing, embossing or like operations on sheetmaterial showing the feed bar arrangement in accordance with the presentinvention;

FIG. 2 is a sectional view taken on lines 2-2 of FIG. 1;

FIG. 3 is an enlarged fragmentary plan view showing three of the feedfinger assemblies of the feed bar constructed in accordance with thepresent invention;

FIGS. 4 and 5 are sectional views taken on lines 4-4 and 5-5respectively of FIG. 3;

FIG. 6 is a sectional view taken on lines 6--6 of FIG. 5 showing theactuator mechanism for one of the feed fingers;

FIG. 7 is a side elevational view showing one of the feed fingerassemblies in a partially forward position in illustrating theconfiguration of a reverse warped blank;

FIG. 8 is a view similar to FIG. 7 showing one of the fingers of thefeed bar assembly during an advance stroke of a skip feed operation;

FIG. 9 is a view similar to FIG. 7 with the actuator mechanism for thefeed finger reverse for use in feeding warped blank material;

FIG. 10 is a perspective view showing the positions of various fingersof the feed bar assembly during feeding of an S warped blank; and

FIG. 11 is a schematic illustration of the electrical and hydrauliccircuitry for the feed bar assembly.

Referring now to the drawings and particularly to FIGS. 1 and 2 thereof,there is shown the feed section of a machine for performing cutting,creasing, printing, embossing or like operations on sheet materials, forexample box blanks B. The feed section broadly designated by the numeral10 includes a feed table 12 on which a stack of blanks B are supportedin position to be fed through the apparatus, and a pair of feed rolls l4rotatably joumalled between the side walls of the main frame and whichadvance a single sheet at a time through the machine for performance ofvarious operations on the box blank, for example cutting, creasing,printing, embossing. As is conventional, the feed table 12 has means formaintaining the stack of box blanks accurately in a predeterminedposition on the table including a pair of adjustable side guides 16 and17, a pair of back stop members 18 each having a shelf on which thestack is supported in the angular position illustrated in FIG. 2 andfront stops 20 which are adjusted so that the gap between the loweredges thereof and the confronting surface of the feed table is justsufficient for passage of only one of the blanks therethrough at a time.

The feed assembly as best illustrated in FIGS. 1 and 2 comprises anelongated bar 30 extending transversely of the center line of themachine which mounts a plurality of spaced actuating fingers generallydesignated by the numeral 32. The bar is mounted for reciprocatingmovement to advance blanks to the feed rolls l4 and to accomplish thisthe bar is attached to the upper surface of a pair of slides 34 and 36which are closely and slidably confined in longitudinal guide slots 38and 40 in the feed table. These slides are connected through a linkagebroadly designated by the numeral 38a which in turn are mounted on acommon actuating shaft 42 which is connected to a suitable actuatingmeans to effect reciprocating movement of the feed bar assembly asdescribed above to advance box blanks to the nip of the feed rolls 14.

Considering now more specifically the structural details and arrangementof the feed fingers and the fluid operated actuating system for the feedfingers, each of the feed fingers comprises a generally rectangularplate member 50 supported at spaced locations along the length of thefeed bar and pivotally connected as at 52 adjacent the forward edge ofthe feed bar. Each of the plate members has a downwardly curved rear portion 54 and mounted on the rear terminal portion is an arcuate feed clip56 having a pickup face portion 58 which is preferably disposed tangentto the radius of the rear terminal portion (see FIGS. 3, 4 and Each ofthe fingers is normally disposed at an angle to the upper surface of thefeed bar by means of an actuator mechanism 59(see FIGS. 5 and 6).

The actuator mechanism 59 consists in the present instance of ablock-like housing 60 mounted adjacent the rear edge of the feed bar,the housing having a generally cylindrical piston chamber 62 formedtherein within which is mounted a piston member 64. The piston chamberis formed by a cavity extending inwardly from the bottom face of theblock-like housing. In the mounted position the piston chamber is sealedby an O- ring 68 mounted in a circumferentially extending groove 66 inthe lower face of the housing. The piston 64 has an enlarged pistonportion with a groove therein to mount a sealing ring 70, the lower faceof the piston having a projection 72 so that the piston does not blockthe inlet port 76 when it is in the lower position. The piston alsoincludes a pin-like projection 80 extending from its front face whichengages through an opening 82 in the upper wall of the housing 60.

The actuator mechanism further includes a pivotally mounted actuatorassembly 84 consisting of a frame-like member 85, the opposite sidewalls of which are pivotally mounted at the forward edge to the housingas at 86. In the present instance, the pivotal mounting includes a pin88 engaging through an opening 90 in the housing, the pin being retainedby means of conventional lock washers on opposite sides of the housing.The frame further includes a top wall 92 which normally overlies thepiston pin 80 and a rear roller 94 which engages the plate member 50 ofthe spring finger. (See FIGS. 5 and 6.)

Each of the housings mounts in the present instance a T- fitting 100which connects the inlet port to a common line 102 attached to asuitable source of fluid pressure, for example high pressure air, theline 102 including, as illustrated schematically in FIG. 11, a solenoidcontrol valve 104, a pressure regulator 106, and a pressure gauge 108.

Referring now by way of example only to the particular form of circuitarrangement illustrated in FIG. 11, the circuit shown therein providesthe capability of skip-feed operation mentioned hereinafter. To thisend, the solenoid 120 of the solenoid valve 104 is provided with a pairof control leads 122 and 124 which are connected to the power lineterminals 128 and 129 respectively when the feed control switch 130 isin its regular feed" position; more particularly, solenoid lead 122 isconnected directly to power line terminal 128, while control lead 124 isconnected to the other power line terminal 129 by way of the contacts134 and 136 of switch 130 when the switch arm 138 thereof is in itslower or regular feed position as shown in the FIG. 11. Under theseconditions the solenoid valve 104 remains operated at all times, so asto supply air pressure through regulator 106 to the hydraulic actuatormechanism 59 for normal feed operation as described hereinabove. Supplyof power to terminals 128 and 129 may be controlled by the same maincontrol switch (not shown) that supplies power to the rest of themachine.

Feed control switch 130 has two positions other than the regular-feed"position described above, namely an ofi position in which the switch arm138 is connected to switch contact 140 and the skip position in whichthe switch arm is connected to switch control 142. When the switch is inits off position, the connection between power line terminal 128 andsolenoid control lead 122 is opened, whereby the solenoid is deactuatedand the hydraulic valve closed, so that the kick bar 30 remainsdeactuated and feed is discontinued.

In the skip position of switch 130, powerline terminal 128 is connectedto control lead 122 of solenoid by way of the controlled terminals 148and 150 of the flip-flop relay 152. The latter relay is of a knowncommercially-available type having two stable states, a first orhigh-conduction state in which contact 148 is effectively connecteddirectly to contact 150 to pass current through the relay, and a secondor lowconduction state in which the latter two terminals are effectivelyopen-circuited from each other. The flip-flop relay 152 is furthercharacterized by a pair of control terminals 156 and 158 having theproperty that a control pulse supplied between these tenninals iseffective to change the flip-flop relay from either of its conductionstates to the other, and the next-subsequent control pulse is operativeto flip the relay back to its first conduction state. Such devices beingwell known in the art, it will be unnecessary to describe herein theinternal connections, arrangements and details thereof.

The latter pair of control terminals 156 and 158 are connected betweenthe power-line terminals 128 and 130, terminal 158 being connecteddirectly to terminal 129 while control terminal 156 is connected topower-line terminal 128 through the impulse switch sensor 164 and thearm 138 of switch when the latter arm is in its upper or skip" position.When the entire machine is operating, a control pulse is applied betweenthe relay control terminals 156 and 158 each time the impulse switchsensor 164 is closed. As described hereinbefore, the latter switch isclosed each time the linkage 38a moves forward during its normal cycleof operation. Accordingly, it will be appreciated that when the feedcontrol switch 130 is in its skip position, current will be suppliedthrough flip-flop relay 152 to hold solenoid valve 104 open during agiven cycle of operation of the feeder bar 30. The operation of thefeeder bar will then close the impulse switch sensor thereby to apply acontrol pulse between control terminals 156 and 158 of relay 152 andchange it to its non-conductive state; during the next successive cycleof operation of the feeder bar, no current will be supplied to solenoidvalve 104. Accordingly, valve 104 will be closed, so that the hydraulicactuator mechanism 59 is deactuated. During the next stroke of thefeeder bar the impulse switch sensor 164 will again be operated and willcause a voltage pulse to be applied between control terminals 156 and158 of the relay 152, to return the flip-flop relay to itshigh-conduction state, thereby again opening solenoid valve 104 andreactuating the hydraulic actuator mechanism 59 so as to feed the nextsubsequent sheet into the feed rolls.

In overall operation then, with the switch 130 in its lower positionnormal operation is obtained whereby a sheet is fed into the feed rollsduring each cycle of operation of the feeder bar 30. When the latterswitch is in its off position, no such feeding occurs at all; and whenthe latter switch is in its skip position, the hydraulic actuatormechanism 59 is actuated and a sheet delivered to the feed rolls onlyfor every other cycle of the feeder bar.

Considering now briefly the operation of a machine for performingcutting, creasing, crimping, embossing, and like operations on sheetmaterial which incorporates the feed bar assembly of the presentinvention, assume that there is a stack of boards at the feeding stationwhich are supported at a predetermined height above the feed table inthe manner illustrated for example in FIGS. 2 and 4. Assume also thatinitially the sheets are of a size for single feed operation. In thisinstance, the operator positions the selector switch 130 for re gularfeed and now starts the machine by actuating the main switch When themachine is set into operation the feed bar is actuated forwardly fromthe retracted position (FIG. 4) by the linkage 38a and on its forwardtravel the feed clips 56 engage the lowermost board to advance the sameinto the nip of the feed rolls 14 which in turn advance a single blankthrough the machine where various operations are performed on the blank.It is noted at the start of operations that the solenoid valve 104 is inan open position whereby air under pressure is fed into the variousactuator mechanisms for the feed fingers through the line 102. By thisarrangement pressure in the lower portion of the piston chamber movesthe piston assembly 64 upwardly to pivot the actuating frame and in turnthe spring finger upwardly into pressure-applying relation with thelowermost blank in the stack. Accordingly, even if the lowermost boardis warped, each of the fingers assumes a positive gripping position (seeFIG. to preclude the possibility of cocking the lowermost blank whichmay cause the apparatus to jam.

In some instances, for example where large size sheets are being fedthrough the machine, the feed bar mechanism is set in the skip-feedposition, which means that the fingers only engage the rear edge of asheet to advance it through the machine. during every other cycle. Morespecifically, in the present instance when the operator desires to setthe machine for skip-feed operation, the selector switch 130 is simplymoved to this position whereby as noted above during the first cycle ofthe feed bar, the impulse sensor switch 164 through the flip-flop relayactuates the solenoid valve 104 into a position closing off the airsupply so that the feed bar fingers are in a lowered position for thiscycle of operation; that is, out of the range of engagement with thelowermost sheet on the stack (see FIG. 8). During the next cycle, thevalve 104 is opened to again pressurize the system and position thefingers so they engage the rear edge of the lowermost sheet in thestack.

In some instances where the sheet material is severely warped, forexample as illustrated in FIG. 9, it may be necessary or desirable toincrease the angle of the said fingers in order to insure engagementwith the lowermost sheet in the stack. In the present instance, this maybe accomplished very easily by simply rotating the housing 180. It isnoted that the housing may be simply secured to the feed bar byconventional screwtype fasteners.

We claim:

1. A feed bar assembly for apparatus for performing operations on sheetmaterial including a feed station wherein a plurality of sheets aresupported in a stack and means for reciprocating the feed bar to advancesingle sheets to a pair of feed rolls comprising an elongated bar and aplurality of feed fingers mounted along the length of said bar, each ofsaid fingers including a pivotally mounted plate member and a feed clipmounted on said plate member having a pickup portion adapted to engagean edge of one sheet at the bottom of the stack to advance the same tothe feed rolls and actuator means for each of said fingers includingmeans common to all of said actuators operable to apply pressure to allof said feed fingers confronting said one sheet thereby to maintain thefeed fingers in substantially uniform pressure applying relation withsaid sheet thereby to insure positive engagement of each of said feedfingers with the edge of said one sheet during feeding movement of saidfeed bar.

2. A feed bar assembly as claimed in claim 1 wherein each of said feedfingers comprises a plate member pivotally connected to said bar, eachof said plate members having a downwardly curved rear portion and anarcuate feed clip mounted on the curved rear portion having a pickupface portion disposed tangent to the radius of the rear terminalportron.

3. A feed bar assembly as claimed in claim 1 wherein said apparatusincludes means for reciprocating said feed bar between a rearward limitposition and a forward limit position and wherein actuation of said feedbar between said limit positions moves the lowermost sheet in the stackinto the nip of the feed rolls.

4. A feed bar assembly as claimed in claim 3 wherein said feed fingersare adapted between an upper limit position to engage the lowermostsheet in the stack and a lowermost limit position out of engagementtherewith.

5. A feed bar assembly as claimed in claim 4 wherein means is providedfor actuating said feed fingers into the uppermost position during everyother cycle of operation.

6. A feed bar assembly for apparatus for performing operations on sheetmaterial including a feed station wherein a plurality of sheets aresupported in a stack and means for reciprocating the feed bar to advancesingle sheets to a pair of feed rolls comprising an elongated bar and aplurality of feed fingers mounted along the length of said bar, each ofsaid fingers including a pivotally mounted plate member and a feed clipmounted on said plate member having a pickup portion adapted to engagean edge of one sheet at the bottom of the stack to advance the same tothe feed rolls and actuator means adapted to pivot said feed fingersupwardly to insure positive engagement of each of said feed fingers withthe edge of said one sheet, said actuator means comprising a housinghaving a piston chamber therein, a piston mounted in said chamber havingan actuating pin projecting from one face thereof adapted to engage saidfeed finger and fluid means for selectively pressurizing said chamber topivot said feed finger in a direction wherein it engages the edge of thelowermost sheet.

7. A feed bar assembly as claimed in claim 6 wherein said actuator meansincludes a frame pivotally mounted on said housing having roller meansengagable with the plate member of said feed finger.

8. A feed bar assembly for apparatus for performing operations on sheetmaterial including a feed station wherein a plurality of sheets aresupported in a stack and means for reciprocating the feed bar to advancesingle sheets to a pair of feed rolls comprising an elongated bar and aplurality of feed fingers mounted along the length of said bar, each ofsaid fingers including a pivotally mounted plate member and a feed clipmounted on said plate member having a pickup portion adapted to engagean edge of one sheet at the bottom of the stack to advance the same tothe feed rolls and actuator means adapted to pivot said feed fingersupwardly to insure positive engagement of each of said feed fingers withthe edge of said one sheet, a fluid pressure system and means connectingthe system to all of the actuator means for the feed fingers.

9. A feed bar assembly as claimed in claim 8 wherein said systemincludes a high pressure air source, a solenoid control valve, apressure regulator and a pressure gauge.

10. A feed bar assembly as claimed in claim 6 including means forsealing the chamber.

11. A feed bar assembly as claimed in claim 10 wherein said seal meanscomprises an O-ring mounted in a groove in the bottom wall of saidhousing circumscribing said chamber.

1. A feed bar assembly for apparatus for performing operations on sheetmaterial including a feed station wherein a plurality of sheets aresupported in a stack and means for reciprocating the feed bar to advancesingle sheets to a pair of feed rolls comprising an elongated bar and aplurality of feed fingers mounted along the length of said bar, each ofsaid fingers including a pivotally mounted plate member and a feed clipmounted on said plate member having a pickup portion adapted to engagean edge of one sheet at the bottom of the stack to advance the same tothe feed rolls and actuator means for each of said fingers includingmeans common to all of said actuators operable to apply pressure to allof said feed fingers confronting said one sheet thereby to maintain thefeed fingers in substantially uniform pressure applying relation withsaid sheet thereby to insure positive engagement of each of said feedfingers with the edge of said one sheet during feeding movement of saidfeed bar.
 2. A feed bar assembly as claimed in claim 1 wherein each ofsaid feed fingers comprises a plate member pivotally connected to saidbar, each of said plate members having a downwardly curved rear portionand an arcuate feed clip mounted on the curved rear portion having apickup face portion disposed tangent to the radius of the rear terminalportion.
 3. A feed bar assembly as claimed in claim 1 wherein saidapparatus includes means for reciprocating said feed bar between arearward limit position and a forward limit position and whereinactuation of said feed bar between said limit positions moves thelowermost sheet in the stack into the nip of the feed rolls.
 4. A feedbar assembly as claimed in claim 3 wherein said feed fingers are adaptedbetween an upper limit position to engage the lowermost sheet in thestack and a lowermost limit position out of engagement therewith.
 5. Afeed bar assembly as claimed in claim 4 wherein means is provided foractuating said feed fingers into the uppermost position during everyother cycle of operation.
 6. A feed bar assembly for apparatus forperforming operations on sheet material including a feed station whereina plurality of sheets are supported in a stack and means forreciprocating the feed bar to advance single sheets to a pair of feedrolls comprising an elongated bar and a plurality of feed fingersmounted along the length of said bar, each of said fingers including apivotally mounted plate member and a feed clip mounted on said platemember having a pickup portion adapted to engage an edge of one sheet atthe bottom of the stack to advance the same to the feed rolls andactuator means adapted to pivot said feed fingers upwardly to insurepositive engagement of each of said feed fingers with the edge of saidone sheet, said actuator means comprising a housing having a pistonchamber therein, a piston mounted in said chamber having an actuatingpin projecting from one face thereof adapted to engage said feed fingerand fluid means for selectively pressurizing said chamber to pivot saidfeed finger in a direction wherein it engages the edge of the lowermostsheet.
 7. A feed bar assembly as claimed in claim 6 wherein saidactuator means includes a frame pivotally mounted on said houSing havingroller means engagable with the plate member of said feed finger.
 8. Afeed bar assembly for apparatus for performing operations on sheetmaterial including a feed station wherein a plurality of sheets aresupported in a stack and means for reciprocating the feed bar to advancesingle sheets to a pair of feed rolls comprising an elongated bar and aplurality of feed fingers mounted along the length of said bar, each ofsaid fingers including a pivotally mounted plate member and a feed clipmounted on said plate member having a pickup portion adapted to engagean edge of one sheet at the bottom of the stack to advance the same tothe feed rolls and actuator means adapted to pivot said feed fingersupwardly to insure positive engagement of each of said feed fingers withthe edge of said one sheet, a fluid pressure system and means connectingthe system to all of the actuator means for the feed fingers.
 9. A feedbar assembly as claimed in claim 8 wherein said system includes a highpressure air source, a solenoid control valve, a pressure regulator anda pressure gauge.
 10. A feed bar assembly as claimed in claim 6including means for sealing the chamber.
 11. A feed bar assembly asclaimed in claim 10 wherein said seal means comprises an O-ring mountedin a groove in the bottom wall of said housing circumscribing saidchamber.